This invention pertains to a method for the lubrication and simultaneous fuel supply of an internal combustion engine, in which the internal combustion engine is operated with a mixture comprising used vegetable oil lubricant, fresh vegetable oil and Diesel fuel or rape seed oil methyl ester. This invention further pertains to an internal combustion engine which is equipped with a container for the dosed supply of fresh vegetable oil into an engine pan from which exhausted vegetable oil is conducted in doses into a fuel tank and, mixed with fuel, and is then supplied to the engine for combustion.
For the lubrication and fuel supply of internal combustion engines, which operate with spark ignition or with compression ignition, currently still petroleum oils are predominantly used. However, partially or fully synthetic lubricants are also already used which, through the addition of additives, acquire the requisite complex properties desired for technical applications. It is known that the lubrication oil must be changed at specific time intervals because, during operation, active substances are consumed, the basic material ages and the lubricant is contaminated with foreign substances. During the oil change, old oils accumulate which represent a considerable environmental problem. Their disposal entails complicated and expensive ways. In order to avoid the accumulation of old oil, it has already been proposed to recirculate the exhausted lubrication oil into the fuel tank and to combust it in the engine together with the fuel.
DE 31 38 144 A1 discloses a lubricant and fuel cyclic course in particular for Diesel engines of heavy duty trucks in which periodically a given quantity of lubrication oil is extracted from the oil pan of the engine and placed into the fuel tank, such that the extracted quantity is consumed together with the customary Diesel fuel. In addition, an automatically operating configuration for monitoring the level of the lubrication oil is provided in order to maintain the lubrication oil level in the oil pan at a nominal level such that fresh lubrication oil is continuously introduced into the lubricant cyclic course, and simultaneously therewith a periodic purification of the old oil occurs. Hereby the waiting times which are required for an oil change are intended to be decreased, and the lubrication oil is, nevertheless, kept substantially clean and in a fresh condition. By adding continuously fresh lubrication oil, the fraction of additives in the lubrication oil is to be kept at a desired value. Thus, only an oil change, which customarily takes place at intervals, is avoided. A specific quantity of exhausted oil is continuously withdrawn from the lubrication system and a corresponding quantity of fresh oil is continuously introduced into the lubrication system.
DE-OS 30 19 877 a device for changing oil in a fuel-burning engine having an internal combustion with a lubrication system including an oil pan and a fuel system including a fuel tank is known in which, for the self-acting oil change and removal of the exhausted oil, an oil transport system is provided. The oil transport system is for transferring a portion of the exhausted engine oil from the lubrication system to the fuel system in order to mix the exhausted oil portion with the fuel. An oil tank for storing fresh oil is provided and an oil feeding system for supplying fresh oil from the oil tank to the lubrication system is provided. The oil transport system can comprise an oil line whose one end communicates with the lubrication system and whose other end communicates with the fuel system, as well as a valve in the oil line. The oil feeding system can comprise an oil feed line, whose one end is connected with the oil tank and whose other end is connected with the oil pan, and a valve interconnected in this oil feed line. This is intended to solve the task of providing a method and a device for changing oil in a fuel-burning engine, in which exhausted oil does not need to be processed again and oil is changed and exhausted oil is removed automatically.
DE 30 06 903 A1 discloses a method for replacing lubrication oil that has collected in the oil sump of a fuel-burning engine, with the aid of an oil suction pump to be controlled separately. At least the quantity of fresh oil corresponding to the quantity of oil siphoned off is supplied to the fuel-burning engine, in which the oil suction pump mixes dosed quantities of oil from the oil sump of the fuel-burning engine with the fuel of the fuel-burning engine. The quantities of oil are chosen such that, independently of the oil consumption of the fuel-burning engine, within an oil change interval the prescribed oil filling quantity is siphoned off. Further, a device is proposed for carrying out this method. The device comprises a fuel-burning engine with an oil sump in which a constant tankage of lubrication oil is provided, and a separate oil suction pump connected with the oil sump of the fuel-burning engine on its suction side, whereby quantities of oil dosed by the oil suction pump can be removed from the oil sump of the fuel-burning engine and can be supplied to the fuel of the fuel-burning engine. Hereby necessary oil changes are said to be superfluous. The lubrication oil quantity is chosen such that the oil filling quantity is siphoned off independently of the oil consumption of the fuel-burning engine within the oil change intervals specified by the engine manufacturer for the engine type. A control instrument is provided such that only in the case of a fuel filling process, in which a level indicator moves upwardly within a short time, the oil suction pump starts to operate. Simultaneously therewith, lubrication oil and fuel are filled into a fuel tankage container such that good thorough mixing is ensured.
In all engine lubrications provided so far it is of a disadvantage in that, due to the use of petroleum oils, the environment is harmed in an unsatisfactory manner and no measures are provided for adding exhausted oil to the fuel system in dosed quantities.
A method and a device for lubricating an internal combustion engine is also known from the German Patent 39 06 759, in which to the lubrication content of the internal combustion engine during operation fresh lubricant is repeatedly supplied from a fresh oil tank. And, simultaneously therewith to the lubricant content of the internal combustion engine at least partially aged lubricant is repeatedly withdrawn and mixed in doses with the engine fuel for combustion. As a lubricant therein, essentially is used a natural vegetable oil, for example rape seed oil. The at least partially aged oil drawn off via a dosing pump, is subsequently supplied under control to the fuel tank of the internal combustion engine according to the amount of the engine fuel such that a predetermined concentration of the vegetable oil is not exceeded.
In this type of loss lubrication of an internal combustion engine, the finding is utilized that, to the fuel of an internal combustion engine with spark ignition or compression ignition, oil can be added up to a few percent without impairing the engine performance, which oil subsequently is combusted during the fuel combustion. Thereby, on the one hand, to the internal combustion engine during its operation fresh oil is supplied continuously according to the invention, but, on the other hand, the partially aged oil is also continuously withdrawn. Thus, a sufficient tankage of fresh lubrication oil is continuously available for lubrication. Even in the form of exhausted oil, which is supplied to the fuel only in a limited and precisely controlled extent and combusted with it, the natural vegetable oils used herein do not yield any combustion products that are damaging to the environment. Prerequisites for the joint combustion of the exhausted vegetable oil and fuel are control and regulation instruments which control precisely the quantities of vegetable oil drawn out of the oil pan and supplied to the fuel.
There have also been considerations given to employing vegetable oils as fuel in Diesel engines. For this purpose, the methyl esters of natural oils, for example the rape seed methyl ester, have been initially in the forefront of interest. This is so because, since conventional Diesel engines only need to be modified insignificantly, attention subsequently turned to the chemically unaltered natural vegetable oils, which as renewable raw materials that are compatible with the environment, can be used in particular for utility vehicles in the fields of agriculture and forestry as alternatives to petroleum oil products. Therefore a xe2x80x9cVorlxc3xa4ufiger Qualitxc3xa4tsstandard fxc3xcr Rapsxc3x6l als Kraftstoff (preliminary quality standard for rape seed oil as fuel)xe2x80x9d has already been worked out by the team xe2x80x9cDezentrale Pflanzenxc3x6lgewinnung Weihenstephanxe2x80x9d (decentral vegetable oil production Weihenstephan).
The present invention is based on the concept that not only are relatively small quantities of used vegetable oil lubricant removed from the engine pan supplied together with Diesel oil or rape seed oil methyl ester for combustion but, moreover, that relatively large quantities of fresh nonadditive-treated vegetable oil are specifically added to the fuel, which relatively large quantities substitute for corresponding quantities of Diesel fuel.
Subject matter of the instant invention includes a method for the lubrication and simultaneous fuel supply of an internal combustion engine in which, from a container for a vegetable oil, a portion of the fresh vegetable oil is removed in doses, which, after being mixed with additives supplied from a container, is used as a lubricant. Another portion of the fresh vegetable oil is removed from the container for a vegetable oil, and together with the exhausted vegetable oil drawn from an oil pan via an oil line, and the Diesel oil or rape seed oil methyl ester, supplied from a fuel tank, is combusted in the internal combustion engine as fuel.